Concentric Approximation for Fast and Accurate Numerical Evaluation of Nonadiabatic Coupling with Projector...

Area of Science:

• Computational physics and chemistry
• Materials science
• Quantum mechanics

Background:

• Nonadiabatic (NA) coupling is crucial for understanding electronic and nuclear dynamics in materials.
• Current methods for evaluating NA coupling in Kohn-Sham theory with projector augmented-wave (PAW) pseudopotentials are computationally expensive and lack accuracy.
• Accurate NA coupling is essential for molecular dynamics (MD) simulations of condensed matter and molecular systems.

Purpose of the Study:

• To develop an efficient and accurate numerical method for evaluating nonadiabatic (NA) coupling.
• To improve the computational speed and accuracy of NA coupling calculations in electronic structure theory.
• To enable more robust and widespread application of NAMD simulations for materials modeling.

Main Methods:

• Numerical evaluation of NA coupling within the Kohn-Sham representation.
• Utilizing projector augmented-wave (PAW) pseudopotentials commonly employed in electronic structure calculations.
• Leveraging the small atomic displacements in typical molecular dynamics (MD) time steps to simplify NA coupling evaluation within the PAW core region.

Main Results:

• The developed method offers an order of magnitude improvement in accuracy compared to existing techniques.
• The method achieves a computational speed that is 3-4 orders of magnitude faster than exact evaluations.
• Demonstrated accuracy and robustness across three condensed matter systems, irrespective of MD time step variations.
• The approach ensures phase-consistency of NA coupling and aids in identifying trivial crossings of adiabatic states.

Conclusions:

• The novel method provides a significant advancement in the efficient and accurate computation of nonadiabatic coupling.
• This technique enhances the reliability of molecular dynamics simulations for nanoscale, condensed matter, and molecular systems.
• The improved NA coupling evaluation opens new avenues for modeling modern materials and chemical processes with NAMD.